Pharmacokinetics and ex-vivo pharmacodynamics of cefquinome against Klebsiella pneumonia in healthy dogs

The pharmacokinetics and pharmacodynamics of cefquinome against Streptococcus agalactiae in a murine mastitis model

Cefquinome is a new generation cephalosporin that is effective in the treatment of mastitis in animals. In this study, we evaluated the associations between the specific pharmacokinetics and pharmacodynamics (PK/PD) of cefquinome and its antibacterial activity against Streptococcus agalactiae in a mouse model of mastitis. After a single intramammary dose of cefquinome (30, 60, 120, and 240 μg/mammary gland), the concentration of cefquinome in plasma was analysed by liquid chromatography with tandem mass spectrometry (HPLC/MS-MS). The PK parameters were calculated using a one-compartment first-order absorption model. Antibacterial activity was defined as the maximum change in the S. agalactiae population after each dose. An inhibitory sigmoid Emax model was used to evaluate the relationships between the PK/PD index values and antibacterial effects. The duration for which the concentration of the antibiotic (%T) remained above the minimum inhibitory concentration (MIC) was defined as the optimal PK/PD index for assessing antibacterial activity. The values of %T > MIC to reach 0.5-log10CFU/MG, 1-log10 CFU/MG and 2-log10 CFU/MG reductions were 31, 47, and 81%, respectively. When the PK/PD index %T > MIC of cefquinome was >81% in vivo, the density of the Streptococcus agalactiae was reduced by 2-log10. These findings provide a valuable understanding to optimise the dose regimens of cefquinome in the treatment of S. agalactiae infections.

Disposition of Cefquinome in Turkeys (Meleagris gallopavo) Following Intravenous and Intramuscular Administration

The bioavailability and pharmacokinetics in turkeys of cefquinome (CFQ), a broad-spectrum 4th-generation cephalosporin antibiotic, were explored after a single injection of 2 mg/kg body weight by intravenous (IV) and intramuscular (IM) routes. In a crossover design and 3-weeks washout interval, seven turkeys were assigned for this objective. Blood samples were collected prior to and at various time intervals following each administration. The concentration of CFQ in plasma was measured using HPLC with a UV detector set at 266 nm. For pharmacokinetic analysis, non-compartmental methods have been applied. Following IV administration, the elimination half-life (t_1/2ʎz), distribution volume at steady state (Vd_ss), and total body clearance (Cl_tot) of CFQ were 1.55 h, 0.54 L/kg, and 0.32 L/h/kg, respectively. Following the IM administration, CFQ was speedily absorbed with an absorption half-life (t_1/2ab) of 0.25 h, a maximum plasma concentration (C_max) of 2.71 μg/mL, attained (T_max) at 0.56 h. The bioavailability (F) and in vitro plasma protein binding of CFQ were 95.56% and 11.5%, respectively. Results indicated that CFQ was speedily absorbed with a considerable bioavailability after IM administration. In conclusion, CFQ has a favorable disposition in turkeys that can guide to estimate optimum dosage regimes and eventually lead to its usage to eradicate turkey's susceptible bacterial infections.

Cefquinome-Loaded Microsphere Formulations in Protection against Pneumonia with Klebsiella pneumonia Infection and Inflammatory Response in Rats

PURPOSE

This study aimed to compare in vivo activity between cefquinome (CEQ)-loaded poly lactic-co-glycolic acid (PLGA) microspheres (CEQ-PLGA-MS) and CEQ injection (CEQ-INJ) against Klebsiella pneumonia in a rat lung infection model.

METHODS

Forty-eight rats were divided into control group (sham operated without infection and drug treatment), Klebsiella pneumonia model group (KPD + Saline), CEQ-PLGA-MS and CEQ-INJ therapy groups (KPD + CEQ-PLGA-MS and KPD + INJ, respectively). In the KPD + Saline group, rats were infected with Klebsiella pneumonia ATCC 10031. In the KPD + CEQ-PLGA-MS and KPD + INJ groups, infected rats were intravenously injected with 12.5 mg/kg body weight CEQ-PLGA-MS and CEQ-INJ, respectively.

RESULTS

Compared to CEQ-INJ treatment group, CEQ-PLGA-MS treatment further decreased the number of bacteria colonies (decreased to 1.94 lg CFU/g) in lung tissues and the levels of inflammatory cytokine including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-4 (p < 0.05 or p < 0.01) in bronchoalveolar lavage fluid at 48 h. Consistently, a significant decreases of scores of inflammation severity were showed at 48 h in the KPD + CEQ-PLGA-MS treatment group, compared to the KPD + CEQ-INJ treatment group.

CONCLUSION

Our results reveal that CEQ-PLGA-MS has the better therapeutic effect than CEQ-INJ for Klebsiella pneumonia lung infections in rats. The vehicle of CEQ-PLGA-MS as the promising alternatives to control the lung infections with the important pathogens.

In vivo pharmacokinetic/Pharmacodynamic modeling of Enrofloxacin against Escherichia coli in broiler chickens

Background

Systemic Escherichia coli infections cause early mortality of commercial broiler chickens. Although enrofloxacin has long been used in poultry, the in vivo pharmacokinetic/pharmacodynamic (PK/PD) relationship of enrofloxacin against E. coli is unclear. The present study aimed to establish an in vivo PK/PD model of enrofloxacin against E. coli in seven-day-old chicks and to ascertain whether the selection of target organ for PD determination is critical for parameter magnitude calculation in enrofloxacin PK/PD modeling.

Results

The in vivo effectiveness of enrofloxacin against E. coli in different organs varied, with the E_max ranging from − 4.4 to − 5.8 Log₁₀ colony forming units (cfu)/mL or cfu/g. Both the surrogate AUC_0–24/MIC of enrofloxacin or AUC_0–24/MIC of the combination of enrofloxacin and ciprofloxacin correlated well with effectiveness in each organ. The AUC_0–24/MIC ratio of the combination of enrofloxacin and ciprofloxacin producing bactericidal and elimination effects were 21.29 and 32.13 in blood; 41.68, and 58.52 in the liver; and 27.65 and 46.22 in the lung, respectively.

Conclusions

The in vivo effectiveness of enrofloxacin against E. coli in different organs was not identical after administration of the same dosage. To describe the magnitude of PK/PD parameter exactly, bacterial loading reduction in different organs as PD endpoints should be evaluated and compared in PK/PD modeling. The selection of a target organ to evaluate PDs is critical for rational dosage recommendation.

Pharmacokinetic and Pharmacodynamic Evaluation of Marbofloxacin in Pig against Korean Local Isolates of Actinobacillus pleuropneumoniae

The pharmacokinetics of marbofloxacin in pigs after intravenous (i.v.), intramuscular (i.m.), and peroral (p.o.) administration and pharmacokinetic/pharmacodynamic indices of this drug against Korean local isolates of Actinobacillus pleuropneumoniae were determined in this study. Marbofloxacin (2.50 mg/kg of body weight) was administered, and blood samples were collected with designated time intervals. Plasma-extracted marbofloxacin was injected into the LC-MS/MS system. The in vitro and ex vivo antibacterial activities of marbofloxacin were evaluated against 20 isolates of A. pleuropneumoniae. The mean peak plasma concentrations (C_max) after i.v., i.m., and p.o administration were 2.60 ± 0.10, 2.59 ± 0.12, and 2.34 ± 0.12 µg/mL at 0.25 ± 0.00, 0.44 ± 0.10, and 1.58 ± 0.40 h, respectively. The area under the plasma concentration-time curves (AUC_0–24) and elimination half-lives were 24.80 ± 0.90, 25.80 ± 1.40, and 23.40 ± 5.00 h·μg/mL and 8.60 ± 0.30, 12.80 ± 1.10, and 8.60 ± 0.00 h, for i.v., i.m., and p.o. administration, correspondingly. The AUC_0–24/MICs of marbofloxacin after i.v., i.m., and p.o. administration were 253.86 ± 179.91, 264.1 ± 187.16, and 239.53 ± 169.75 h, respectively. The C_max/MIC values were 26.58 ± 18.84, 26.48 ± 18.77, and 23.94 ± 16.97, and T>MICs were 42.80 ± 1.01, 36.40 ± 1.24, and 38.60 ± 1.18 h, after i.v., i.m., and p.o. administration, respectively. Thus, marbofloxacin dosage of 2.50 mg/kg of body weight by i.v., i.m., and p.o. administration with 24 h dosing interval will provide effective treatment for the infection of pig by A. pleuropneumonia.

In vitro susceptibility of four antimicrobials against Riemerella anatipestifer isolates: a comparison of minimum inhibitory concentrations and mutant prevention concentrations for ceftiofur, cefquinome, florfenicol, and tilmicosin

Background

Mutant prevention concentration (MPC) is an alternative pharmacodynamic parameter that has been used to measure antimicrobial activity and represents the propensities of antimicrobial agents to select resistant mutants. The concentration range between minimum inhibitory concentration (MIC) and MPC is defined as mutant selection window (MSW). The MPC and MSW parameters represent the ability of antimicrobial agents to inhibit the bacterial mutants selected. This study was conducted to determine the MIC and MPC values of four antimicrobials including ceftiofur, cefquinome, florfenicol and tilmicosin against 105 Riemerella anatipestifer isolates.

Results

The MIC₅₀/MIC₉₀ values of clinical isolates tested in our study for ceftiofur, cefquinome, florfenicol and tilmicosin were 0.063/0.5、0.031/0.5、1/4、1/4 μg/mL, respectively; MPC₅₀/ MPC₉₀ values were 4/64、8/64、4/32、16/256 μg/mL, respectively. These results provided information on the use of these compounds in treating the R. anatipestifer infection; however, additional studies are needed to demonstrate their therapeutic efficacy.

Conclusion

Based on the MSW theory, the hierarchy of these tested antimicrobial agents with respect to selecting resistant subpopulations was as follows: cefquinome > ceftiofur > tilmicosin > florfenicol. Cefquinome was the drug that presented the highest risk of selecting resistant mutant among the four antimicrobial agents.

Activity of cefquinome against extended-spectrum β-lactamase-producing Klebsiella pneumoniae in neutropenic mouse thigh model

Increasing prevalence of extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae (K. pneumoniae) is of clinical concern. The objective of our study was to examine the in vivo activity of cefquinome against ESBL-producing K. pneumoniae strain using a neutropenic mouse thigh infection model. Cefquinome kinetics and protein binding in infected neutropenic mice were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Dose-fractionation studies over a 24-h dose range of 2.5-320 mg/kg were administered every 3, 6, 12, or 24 h. The percentage of the dosing interval that the free-drug serum levels exceed the MIC (%fT > MIC) was the PK-PD index that best correlated with cefquinome efficacy (R²  = 86%). Using a sigmoid E_max model, the magnitudes of %fT > MIC producing net bacterial stasis, a 1-log₁₀ kill and a 2-log₁₀ kill over 24 h, were estimated to be 20.07%, 29.57%, and 55.12%, respectively. These studies suggest that optimal cefquinome PK/PD targets are not achieved in pigs, sheep, and cattle at current recommended doses (1˜2 mg/kg). Further studies with higher doses in the target species are needed to ensure therapeutic concentration, if cefquinome is used for treatment of K. pneumoniae infection.